1. Field of the Invention
This invention relates generally to dispensing measured amounts of fluids. More particularly, this invention relates to a valve assembly for dispensing accurately measured volumes of sensitive fluids with a minimum of damage to the fluid.
2. Description of the Prior Art
Research and commercial establishments require the facility of being able to dispense accurately measured amounts of fluids on a repetitive basis. The prior art discloses fluid dispensing systems that transfer a fluid from a source point to a dispensing point. Some of these systems calibrate the volume of fluid transferred. Once the calibrated volume of fluid has been transferred to a dispensing point, the fluid must be dispensed from the system, typically into a waiting container. Frequently, as on a production line, a measured volume of fluid must be dispensed repeatedly into a series of containers.
When the fluid to be dispensed is delicate, such as blood solutions, it is important that the means used to dispense the fluid does not damage the fluid. It is also important that the dispensing means does not influence the fluid volume preselected for dispensing. If a dispensing means alters that preselected volume, the accuracy of the calibrated amount is lost, and different containers may not contain the same volume of fluid. Where dispensing the fluid volume is repeated, it is important that the fluid is dispensed cleanly, with no dripping of fluid which could contaminate the necks and exterior surfaces of containers, or the support and transfer system of the containers. Finally, it is important that any dispensing means can be rapidly and easily cleaned for reuse with a different fluid.
To applicant's knowledge there is no dispensing valve assembly disclosed in the prior art that can meet these requirements.
Applicant's invention fills the need for a dispensing valve assembly that can dispense measured volumes of fluid repetitively with a high degree of accuracy. The action of the valve assembly of the invention preserves a preselected volume received from a calibrated pump. The design of applicant's invention enables it both to be directly associated with such a pump and to dispense directly into fluid containers, so eliminating the need for long fluid supply lines, which can increase the probability of volumetric error.
The present invention also fills the need for a dispensing means that is protective of delicate fluid, as the invention presents only a minimum crushing area to the fluid.
The present invention also fills the need for a nondripping dispensing means, as the pumping action of the invention at the end of the dispensing cycle, sucks back fluid from the outlet point. This antidrip feature of the present invention is achieved while avoiding a backup of air into the invention, thus avoiding foaming of the fluid, which would introduce both errors in volume dispensing and the possibility of damage to the fluid.
The present invention fills these needs and also provides a dispensing valve assembly that can be quickly and easily disassembled for cleaning.